B M S Kumar

In the present study a simple isocratic reverse phase HPLC method was developed for the estimation of rilpivirine in pharmaceutical formulation. The separation was carried out using a column of Zorbax Eclipse XDB-C18, 250x4.6mmi.d with 5micron particle size. The mobile phase comprises of 0.03M di potassium hydrogen orthophosphate with pH adjusted to 2.5 using dilute ortho-phosphoric acid (mobile phase solvent-A) and acetonitrile (mobile phase solvent-B) in the ratio of 15: 85 (v/v).The flow rate was 1.0 ml/min and the effluents were monitored at 284 nm. The retention time was 7.19 min. The detector response was linear in the concentration range of 100-300µg/ml. The respective linear regression equation being Y= 28817.742X-14741.2. The limit of detection (LOD) and limit of quantification (LOQ) for rilpivirine were found to be 0.05µg/ml and 0.15 µg/ml respectively. The assay was found to be 99.85%.The method was validated by determining its accuracy, precision and system suitability. The results of the study showed that the proposed RP-HPLC method is simple, rapid, precise and accurate, which is useful for the routine determination of rilpivirine in its pharmaceutical dosage form.

A simple, sensitive, selective and rugged liquid chromatography coupled with mass spectrometry (LC/MS/MS) method for quantification of Diltiazem and its metabolites, N-desmethyl Diltiazem, desacetyl Diltiazem in human plasma was developed and validated. The chromatography was developed using Luna 5 μ, C18, 100×4.60 mm column having a mobile phase of Acetonitrile: 0.1 % formic acid (85:15 % v/v). The flow rate was 0.5 ml/min at a column temperature of 50 ± 5º C. Electron spray ionization technique in positive mode was selected to improve the selectivity and sensitivity required for this application. The retention times of Diltiazem, desmethyl Diltiazem, desacetyl Diltiazem were 2.5, 2.0 and 2.5 minutes respectively. The method was validated for linearity, precision, accuracy, specificity, sensitivity, matrix effect, dilution integrity, ruggedness, injection reproducibility and stability. Calibration curves during the course of validation were found to be linear for Diltiazem, desmethyl Diltiazem, desacetyl Diltiazem in the ranges of 0.604-603.902, 0.303-303.274 and 0.299-299.489 ng/mL with correlation coefficient ≥ 0.9969, 0.9958 and 0.9970 respectively and by using a 1/x2 weighted least square regression analysis of standard plots associated with ten point calibration standards. The precision and mean accuracy were within the acceptable limits.